As processing capabilities are enhanced in processors, one concern is the speed at which memory may be accessed by a processor. For example, to process data, a processor may need to first fetch data from a memory. After completion of the processing, the results may need to be stored in the memory. Therefore, the memory speed can have a direct effect on overall system performance.
Another important consideration is power consumption. For example, in mobile computing devices that rely on battery power, it is very important to reduce power consumption to allow for the device to operate while mobile. Power consumption is also important for non-mobile computing devices as excess power consumption may increase costs (e.g., due to additional power usage, increasing cooling requirements, etc.), shorten component life, limit locations at which a device may be used, etc.
Hard disk drives provide a relatively low-cost storage solution and are used in many computing devices to provide non-volatile storage. Disk drives however use a lot of power when compared to flash memory since a disk drive needs to spin its disks at a relatively high speed and move disk heads relative to the spinning disks to read/write data. All this physical movement generates heat and increases power consumption. To this end, some higher end mobile devices are migrating towards flash memory devices that are non-volatile. However, flash memory has a number of drawbacks including, for example, relatively large voltage level requirement to change bit states, delay in write times due to requirement of a charge pump ramp up, having to erase a block of cells at a time, etc
Phase Change Memory (PCM) is another type of non-volatile memory that may provide higher performance and/or endurance when compared to a flash memory device. For example, PCM allows a single bit to be changed without needing to first erase an entire block of cells, PCM structure may degrade more slowly, PCM data state may be retrained for a relatively longer period, and PCM is more scalable.